Hydraulic plunger seal



Nov. 7, 1939. R. CHILTON HYDRAULIC PLUNGER SEAL Filed Oct. 16, 1957Illll 1 N VE N TOR. KOLHND Mara/v ATTORNEY.

Patented Nov. 7, 1939 UNITED STATES PATENT OFFICE HYDRAULIC PLUNGER SEALRoland Chilton, Ridgewood, N. J., assignor to Wright AeronauticalCorporation, a corporation of New York Application October 16, 1937,Serial No. 169,350 4 Claims. (01(137-157) in the art and comprise aflexible sleeve, usually of rubber, having inner and outer cylindricalparts so that the inner part may move relatively to the outer, part by arolling action, whereby material is paid off around the joining elementfrom the inner to the outer parts in one direction of movement and viceversa in the other, as in the process of turning a stocking" inside out.

The prime feature of the present invention consists in a. special methodof reinforcing the seal member by flexible cords having a noveldisposition whereby elastic stretch of the rubber element under fluidpressure is prevented without in any way impairing the ability of theflexible material to roll in operation to transfer itself from theinnerand outer circumferences.

Other objects will be obvious from, or will be pointed out in thefollowing description, with reference to the drawing, in which:

Fig. 1 is an axial section of a cylinder-plunger incorporating a seal;

Fig. 2 is a transverse section on the line 2-2 of Fig. 1;

Fig. 3 is a developmentof the seal alone;

' Fig. 4 is a development of an alternative seal, and

Fig. 5 is an axial section through a cylinderplunger incorporating'theseal of Fig. 4.

In the drawing, I0 designates a cylinder element in which is slidablyfitted a plunger l2 having a projecting head l4 of reduced diameter. Aflexible seal l5 between the cylinder l0 and the head I4 comprises abead IS, an outer tubular portion l8 and an inner tubular portion 20,joined by the rolled portion 22, a head portion 24 completing the sealand overlapping the head l4. The seal l5 comprises a flexible diaphragmbridging the head I4 and the cylinder Ill and allowing movementtherebetween.

Reinforcing cords 26 extend from the head it through the wall portions|8--20-22 across the head 24 downthe diametrically opposite wallportions back up to the head It. Within this bead the cords may bewrapped around a form ring 25 and the entire reinforcement may be laidup from a single length of cord 26, the individual cord runs crossingover'each other within the thickened head 24 as shown at 21. The cordstructure is then imbedded in rubber by vulcanization to comprise theintegral sealing unit.

It is an important provision of the invention 5 that the cords in thewalls run longitudinally of the seal I5 only. It will be seen thatshould the plunger be moved upwardly, for example, material is paid offfrom the cylinder ID on to the smaller diameter plunger I4 wherein the10 cords are accordingly closer spaced than in the 'outer portion l8 asis clear from Fig. 2 and for the same reason the thickness of rubber onthe inner portion 20 is greater than in the outer portion I8 inproportion to the different cir- 15 cumferences. It will be seen thatthe longitudinal cords in no way stiffen the structure against thesechanges in circumference and thickness as would any woven fabric orother reinforcements having circumferential elements. The bead I610 isclamped at assembly by a suitable cover 28 having a pressure connection30.

It will be seen that when fluid pressure is applied beneath the cover28, the load is taken in tension by the cords 26 which, beingsubstantially non-stretchable as compared with the rubber, give theentire structure volumetric rigidity and permit high pressures to becarried despite the fact that the rubber itself is highly elastic andextensible. In other words, the rubso ber afiords complete fluidtightness while the cords carry the operating loads.

In the drawing, the spacing of the cords has been exaggerated. Inpractice, they will be so spaced as to be close together when on thecon- 35 tracted portion 20. If, for example strands of cord like thatwhich appears in Fig. 1 be used, the operating load will be distributedover 200 working portions of the cords. In this way, a structure capableof carrying very high pressures 4c; is afforded. At the same time, anon-porous elastic material and a tight clamp on the head It isall thatis needed to insure zero leakage which cannot be affected by operatingmovement of the plunger and is quite independent 45 of the plunger flt.

The natural curvature assumed by the seals l5 and 3| due to theirdistortion from large to small diameter conforms to the shape which theywill assume under fluid pressure which again 50 contributes to theobjective of volumetric rigidity in the assembled device. If desired,the vulcanizing dies may take the form appropriate to Figs. 3 and 4wherein the wall elements are molded as a straight taper extending fromthe u head to the bead, the sleeve so formed being turned partly insideout" before assembhr. This particular method will involve the beadsection rotating relative to the end ring if this be made of wire orother rigid material, in which case it may be desirable to coat themetallic rings 25, 32 or 34 with some substance inhibiting adhesion ofthe cord and rubber thereto.

Figs. 4 and 5 show an alternative embodiment wherein a sealing sleeve 3|is provided with end rings 32 and 34 over which a cord 36 is reeved, thewhole sleeve being impregnated with rubber, as shown. The large-sleeveend is held between thehousing l0 and the cover 28, while the smallsleeve end is drawn inwardly within the larger sleeve end, the smallerend being clamped to the end of the plunger '14 by a cap 38 and a screwin.

The two arrangements operate in the same manner, the sleeves beingdiflerent only at that end which is engaged by the end of the plungerll.

While I have described my invention in detail in its present preferredembodiment, it will be obvious to those skilled in the art, aiterunderstanding my invention, that various changes and modifications maybe made therein without departing from the spirit or scope thereof. Iaim in the appended claims to cover all such modifications and changes.

I claim as my invention:

1. A non-stretchable seal for piston and cylinder members comprising aflexible U section annulus contacting respective members, a closing headintegral with the inner limb of the U and a bead integral with the outerlimb oi. the U and cords extending through said seal betweendiametrically opposed points on said bead, said cords lying radially insaid head and in the curved part 01 the seal between said limbs andlying longitudinally in said limbs.

2. As an article of manufacture, a tapered rubber sleeve closed at itssmaller'end, a ring at the larger end, and cords, imbedded in therubber, reeved from said ring longitudinally along one side 01 thesleeve, radially across the closed end and in overlapping relation withprior and successive runs of the cord, and longitudinally along thediametrically opposite side of the sleeve to said ring.

3. A diaphragm for sealing a plunger relative to a cylinder comprising arubber conical trustum having a ring at its larger end, the irustumbeing integrally closed at its smaller end by rubber; and a singlere-eniorcing cord reeved from said ring along a conical element, acrossthe closed small end and back to the ring along a conical elementsubstantially diametrically opposed to the first said element, aroundsaid ring and similarly back and forth along conical elements; so thatcord runs lie adjacent to one another throughout the periphery oi theimstum, said cord runs lying one over the other at the closed end of thediaphragm. said cord, including all the runs thereof, being embedded inthe rubber of the diaphragm.

4. As an article of manuiacture, a diaphragm comprising a conicalirustum of rubber closed by the rubber at its smaller end, a metallicring embedded in the rubber at its larger end; and a reinforcing cord,embedded throughout in the rubber, reeved back and iorth, around thering, along a conical element 01 the irustuln, radially across theclosed end, along a conical element substantially diametrically oppositeto the first and around the ring; the successive cord runs in theaggregate forming longitudinally extending reinforcements, throughoutthe periphery of the irustum, between the ring and the closed end.

ROLAND CHILTON.

